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Here is the FITS version of the first extension header of the FITS version of the catalog, with the changes specified above adopted. Actually, this is pseudo-FITS, as the comments are not properly set off, but all of the columns and keywords are present.
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XTENSION = 'BINTABLE' Extension type BITPIX 8 Bits per pixel - assume single precision floating point NAXIS 2 # of axes=2 NAXIS1 ### Number of bytes per row NAXIS2 ### Number of point sources in file (~1e4) TFIELDS 27 Number of fields per row CHECKSUM Checksum for entire HDU DATASUM Checksum for data table TELESCOP 'GLAST' Name of mission generating data INSTRUME 'LAT' EXTNAME 'LAT_Point_Source_Catalog' Name of the extension TIMESYS 'TT' Time system used in time keywords MJDREF 51910 MJD date of reference epoch TIMEUNIT 's' Time unit used in TSTART, TSTOP and TZERO keywords TSTART ### Time of start of observation offset from TZERO in units of TIMEUNIT TSTOP ### Time of end of observation offset from TZERO in units of TIMEUNIT HDUCLASS 'OGIP ' Format conforms to OGIP standard HDUDOC '?' HDUVERS '1.0.0 ' HDUCLAS1 'SRCLIST' ? TTYPE1 'Source_Name' Source name in standard format, e.g., 1GL J123456-012345 TFORM1 '18A ' Character string TUNIT1 'none' Units of field TTYPE2 'RA' TFORM2 '1E ' Floating point TUNIT2 'deg' TLMIN2 0.0 Minimum value TLMAX2 360.0 Maximum value TTYPE3 'DEC' DEC TFORM3 'E ' Floating point TUNIT3 'deg' TLMIN3 -90.0 Minimum value TLMAX3 90.0 Maximum value TTYPE4 'Conf_68_SemiMajor' Semimajor axis, 68% containment confidence region TFORM4 '1E ' Floating point TUNIT4 'deg' TLMIN4 0.0 Minimum value TLMAX4 360.0 Maximum value TTYPE5 'Conf_68_SemiMinor' Semiminor, axis, 68% containment confidence region TFORM5 '1E ' Floating point TUNIT5 'deg' TLMIN5 0.0 Minimum value TLMAX5 360.0 Maximum value TTYPE6 'Conf_68_PosAng' Position angle, 68% containment confidence region, E of N TFORM6 '1E ' Floating point TUNIT6 'deg' TLMIN6 0.0 Minimum value TLMAX6 360.0 Maximum value TTYPE7 'Conf_95_SemiMajor' Semimajor axis, 95% containment confidence region TFORM7 '1E ' Floating point TUNIT7 'deg' TLMIN7 0.0 Minimum value TLMAX7 360.0 Maximum value TTYPE8 'Conf_95_SemiMinor' Semiminor, axis, 95% containment confidence region TFORM8 '1E ' Floating point TUNIT8 'deg' TLMIN8 0.0 Minimum value TLMAX8 360.0 Maximum value TTYPE9 'Conf_95_PosAng' Position angle, 95% containment confidence region, E of N TFORM9 '1E ' Floating point TUNIT9 'deg' TLMIN9 0.0 Minimum value TLMAX9 360.0 Maximum value TTYPE6 'Flux100' Average photon flux >100 MeV TFORM6 '1E ' Floating point TUNIT6 'cm**(-2) s**(-1)' TLMIN6 0.0 Minimum value TLMAX6 ### Maximum value TTYPE7 'Unc_Flux100' Uncertainty (1-sigma) in average flux >100 MeV TFORM7 '1E ' Floating point TUNIT7 'cm**(-2) s**(-1)' TLMIN7 0.0 Minimum value TLMAX7 ### Maximum value TTYPE8 'Spectral_Index' Photon spectral index, >100 MeV TFORM8 '1E ' Floating point TUNIT8 'none' Dimensionless TLMIN8 -10.0 Minimum value TLMAX8 10.0 Maximum value TTYPE8 'Unc_Spectral_Index' 1-sigma uncertainty, photon spectral index TFORM8 '1E ' Floating point TUNIT8 'none' Dimensionless TLMIN8 0.0 Minimum value TLMAX8 10.0 Maximum value TTYPE9 'Flux300' Average flux >300 MeV TFORM9 '1E ' Floating point TUNIT9 'cm**(-2) s**(-1)' TLMIN9 0.0 Minimum value TLMAX9 1.0 Maximum value TTYPE10 'Unc_Flux300' Uncertainty (1-sigma) in average flux >300 MeV TFORM10 '1E ' Floating point TUNIT10 'cm**(-2) s**(-1)' TLMIN10 0.0 Minimum value TLMAX10 1.0 Maximum value TTYPE11 'Flux1000' Average flux >1000 MeV TFORM11 '1E ' Floating point TUNIT11 'cm**(-2) s**(-1)' TLMIN11 0.0 Minimum value TLMAX11 1.0 Maximum value TTYPE12 'Unc_Flux1000' Uncertainty (1-sigma) in average flux >1000 MeV TFORM12 '1E ' Floating point TUNIT12 'cm**(-2) s**(-1)' TLMIN12 0.0 Minimum value TLMAX12 1.0 Maximum value TTYPE13 'Flux3000' Average flux >3000 MeV TFORM13 '1E ' Floating point TUNIT13 'cm**(-2) s**(-1)' TLMIN13 0.0 Minimum value TLMAX13 1.0 Maximum value TTYPE14 'Unc_Flux3000' Uncertainty (1-sigma) in average flux >3000 MeV TFORM14 '1E ' Floating point TUNIT14 'cm**(-2) s**(-1)' TLMIN14 0.0 Minimum value TLMAX14 1.0 Maximum value TTYPE15 'Variability_Index' Flux variability index (TBD) TFORM15 '1E ' Floating point TUNIT15 'none' Dimensionless TLMIN15 ### Minimum value TLMAX15 ### Maximum value TTYPE16 'Signif_Avg' Detection significance (whole time interval) TFORM16 '1E ' Floating point TUNIT16 'none' Dimensionless TLMIN16 0.0 Minimum value TLMAX16 1.0E9 Maximum value TTYPE17 'Signif_Peak' Detection significance (peak) TFORM17 '1E ' Floating point TUNIT17 'none' Dimensionless TLMIN17 0.0 Minimum value TLMAX17 1.0E9 Maximum value TTYPE18 'Flux_Peak' Peak flux (>100 MeV) for time interval above TFORM18 '1E ' Floating point TUNIT18 'cm**(-2) s**(-1)' TLMIN18 0.0 Minimum value TLMAX18 1.0 Maximum value TTYPE19 'Unc_Peak_Flux' Uncertainty (1-sigma) in peak flux >100 MeV TFORM19 '1E ' Floating point TUNIT19 'cm**(-2) s**(-1)' TLMIN19 0.0 Minimum value TLMAX19 1.0 Maximum value TTYPE20 'Time_Peak' Center of time interval of peak significance TFORM20 '1D ' Double precision TUNIT20 's' TLMIN20 0.0 Minimum value TLMAX20 ### Maximum value TZERO20 ### TTYPE21 'Peak_Interval' Duration of time interval of peak significance TFORM21 '1D ' Double precision TUNIT21 's' TLMIN21 0 Minimum value TLMAX21 ### Maximum value TTYPE22 'Flux_History' Flux (>100 MeV) history (monthly) TFORM22 '12E ' Floating point array, 12 months TUNIT22 'cm**(-2) s**(-1)' TLMIN22 -1.0 Minimum value TLMAX22 1.0 Maximum value TTYPE23 'Flux_Unc_History' Flux uncertainty (1-sigma, >100 MeV) history TFORM23 '12E ' Floating point array, 12 months TUNIT23 'cm**(-2) s**(-1)' TLMIN23 0.0 Minimum value TLMAX23 1.0 Maximum value TTYPE24 'Hist_Start' Start of time intervals of flux history TFORM24 '12E ' Floating point array TUNIT24 's' TLMIN24 0.0 Minimum value TLMAX24 ### Maximum value TZERO24 ### TTYPE25 'ID_Counterpart' Source counterpart (if any) TFORM25 '20A ' Character string TUNIT25 'none' Dimensionless TTYPE26 'Conf_Counterpart' Confidence of association of counterpart with source TFORM26 '1I ' Index, 1 = Figure of Merit, 2 = Correlated variability TUNIT26 'none' Dimensionless TLMIN26 0 Minimum value TLMAX26 2 Maximum value TTYPE27 'Flags' Flags (TBD) for catalog entry TFORM27 '1I ' TUNIT27 'none' Dimensionless END |
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/ binary table extension
BITPIX = 8 / 8-bit bytes
NAXIS = 2 / 2-dimensional binary table
PCOUNT = / size of special data area
GCOUNT = 1 / one data group (required keyword)
TFIELDS = 32 / number of fields in each row
CHECKSUM = / checksum for entire HDU
DATASUM = / checksum for data table
TELESCOP = 'GLAST' / name of telescope generating data
INSTRUME = 'LAT' / name of instrument generating data
EQUINOX = 2000.0 / equinox for ra and dec
RADECSYS = 'FK5' / world coord. system for this file (FK5 or FK4)
EXTNAME = 'LAT_Point_Source_Catalog' / name of this binary table extension
HDUCLASS = 'OGIP' / format conforms to OGIP standard
HDUCLAS1 = 'EVENTS' / extension contains events
HDUCLAS2 = 'ALL' / extension contains all events detected
TSTART = / mission time of the start of the observation
TSTOP = / mission time of the end of the observation
TIMEUNIT = 'd' / units for the time related keywords
TIMEZERO = 0.0 / clock correction
TIMESYS = 'MJD' / type of time system that is used
TIMEREF = 'LOCAL' / reference frame used for times
DATE = / file creation date (YYYY-MM-DDThh:mm:ss UT)
DATE-OBS = / start date and time of the observation (UTC)
DATE-END = / end date and time of the observation (UTC)
NDSKEYS = 0 / number of data subspace keywords in header
HDUCLASS = 'OGIP ' / format conforms to OGIP standard
HDUDOC = '?' / document describing the format
HDUVERS = '1.0.0 ' / version of the format
HDUCLAS1 = 'SRCLIST' / an OGIP standard class
TTYPE1 = 'Source_Name' / e.g., 1GL J123456-012345
TFORM1 = '18A ' / character string
TUNIT1 = 'none' / units of field
TTYPE2 = 'RA' / right ascension of source
TFORM2 = 'E' / floating point
TUNIT2 = 'deg' / units of field
TLMIN2 = 0.0 / minimum value
TLMAX2 = 360.0 / maximum value
TTYPE3 = 'DEC' / declination of source
TFORM3 = 'E' / floating point
TUNIT3 = 'deg' / units of field
TLMIN3 = -90.0 / minimum value
TLMAX3 = 90.0 / maximum value
TTYPE4 = 'Conf_68_SemiMajor' / semimajor axis, 68% containment confidence region
TFORM4 = 'E' / floating point
TUNIT4 = 'deg' / units of field
TLMIN4 = 0.0 / minimum value
TLMAX4 = 360.0 / maximum value
TTYPE5 = 'Conf_68_SemiMinor' / semiminor, axis, 68% containment confidence region
TFORM5 = 'E' / floating point
TUNIT5 = 'deg' / units of field
TLMIN5 = 0.0 / minimum value
TLMAX5 = 360.0 / maximum value
TTYPE6 = 'Conf_68_PosAng' / position angle, 68% containment confidence region, E of N
TFORM6 = 'E' / floating point
TUNIT6 = 'deg' / units of field
TLMIN6 = 0.0 / minimum value
TLMAX6 = 360.0 / maximum value
TTYPE7 = 'Conf_95_SemiMajor' / semimajor axis, 95% containment confidence region
TFORM7 = 'E' / floating point
TUNIT7 = 'deg' / units of field
TLMIN7 = 0.0 / minimum value
TLMAX7 = 360.0 / maximum value
TTYPE8 = 'Conf_95_SemiMinor' / semiminor, axis, 95% containment confidence region
TFORM8 = 'E' / floating point
TUNIT8 = 'deg' / units of field
TLMIN8 = 0.0 / minimum value
TLMAX8 = 360.0 / maximum value
TTYPE9 = 'Conf_95_PosAng' / position angle, 95% containment confidence region, E of N
TFORM9 = 'E' / floating point
TUNIT9 = 'deg' / units of field
TLMIN9 = 0.0 / minimum value
TLMAX9 = 360.0 / maximum value
TTYPE10 = 'Flux100' / average photon flux >100 MeV
TFORM10 = 'E' / floating point
TUNIT10 = 'cm**(-2) s**(-1)' / units of field
TLMIN10 = 0.0 / minimum value
TLMAX10 = 1.0 / maximum value
TTYPE11 = 'Unc_Flux100' / uncertainty (1-sigma) in average flux >100 MeV
TFORM11 = 'E' / floating point
TUNIT11 = 'cm**(-2) s**(-1)' / units of field
TLMIN11 = 0.0 / minimum value
TLMAX11 = 1.0 / maximum value
TTYPE12 = 'Flux300' / average photon flux >300 MeV
TFORM12 = 'E' / floating point
TUNIT12 = 'cm**(-2) s**(-1)' / units of field
TLMIN12 = 0.0 / minimum value
TLMAX12 = 1.0 / maximum value
TTYPE13 = 'Unc_Flux300' / uncertainty (1-sigma) in average flux >300 MeV
TFORM13 = 'E' / floating point
TUNIT13 = 'cm**(-2) s**(-1)' / units of field
TLMIN13 = 0.0 / minimum value
TLMAX13 = 1.0 / maximum value
TTYPE14 = 'Flux1000' / average photon flux >1000 MeV
TFORM14 = 'E' / floating point
TUNIT14 = 'cm**(-2) s**(-1)' / units of field
TLMIN14 = 0.0 / minimum value
TLMAX14 = 1.0 / maximum value
TTYPE15 = 'Unc_Flux1000' / uncertainty (1-sigma) in average flux >1000 MeV
TFORM15 = 'E' / floating point
TUNIT15 = 'cm**(-2) s**(-1)' / units of field
TLMIN15 = 0.0 / minimum value
TLMAX15 = 1.0 / maximum value
TTYPE16 = 'Flux3000' / average photon flux >3000 MeV
TFORM16 = 'E' / floating point
TUNIT16 = 'cm**(-2) s**(-1)' / units of field
TLMIN16 = 0.0 / minimum value
TLMAX16 = 1.0 / maximum value
TTYPE17 = 'Unc_Flux3000' / uncertainty (1-sigma) in average flux >1000 MeV
TFORM17 = 'E' / floating point
TUNIT17 = 'cm**(-2) s**(-1)' / units of field
TLMIN17 = 0.0 / minimum value
TLMAX17 = 1.0 / maximum value
TTYPE18 = 'Spectral_Index' / photon spectral index, >100 MeV
TFORM18 = 'E' / floating point
TUNIT18 = 'none' / dimensionless
TLMIN18 = -10.0 / minimum value
TLMAX18 = 10.0 / maximum value
TTYPE19 = 'Unc_Spectral_Index' / 1-sigma uncertainty, photon spectral index
TFORM19 = 'E' / floating point
TUNIT19 = 'none' / dimensionless
TLMIN19 = 0.0 / minimum value
TLMAX19 = 10.0 / maximum value
TTYPE20 = 'Variability_Index' / flux variability index (TBD)
TFORM20 = 'E' / floating point
TUNIT20 = 'none' / dimensionless
TLMIN20 = ### / minimum value (TBD)
TLMAX20 = ### / maximum value (TBD)
TTYPE21 ='Signif_Avg' / detection significance (whole time interval)
TFORM21 = 'E' / floating point
TUNIT21 = 'none' / dimensionless (sigmas)
TLMIN21 = 0.0 / minimum value
TLMAX21 = 1.0E9 / maximum value
TTYPE22 = 'Signif_Peak' / detection significance (peak)
TFORM22 = 'E' / floating point
TUNIT22 = 'none' / dimensionless (sigmas)
TLMIN22 = 0.0 / minimum value
TLMAX22 = 1.0E9 / maximum value
TTYPE23 = 'Flux_Peak' / peak flux (>100 MeV) for time interval above
TFORM23 = 'E' / floating point
TUNIT23 = 'cm**(-2) s**(-1)'
TLMIN23 = 0.0 / minimum value
TLMAX23 = 1.0 / maximum value
TTYPE24 = 'Unc_Peak_Flux' / uncertainty (1-sigma) in peak flux >100 MeV
TFORM24 = 'E' / floating point
TUNIT24 = 'cm**(-2) s**(-1)' / units of field
TLMIN24 = 0.0 / minimum value
TLMAX24 = 1.0 / maximum value
TTYPE25 = 'Time_Peak' / center of time interval of peak significance
TFORM25 = 'D' / double precision
TUNIT25 = 'd' / units of field
TLMIN25 = 0.0 / minimum value
TLMAX25 = 1.0D5 / maximum value
TTYPE26 = 'Peak_Interval' / duration of time interval of peak significance
TFORM26 = 'D' / double precision
TUNIT26 = 's' / units of field
TLMIN26 = 0.0 / minimum value
TLMAX26 = 3.0D7 / maximum value
TTYPE27 = 'Flux_History' / flux (>100 MeV) history (monthly)
TFORM27 = '12E' / floating point array, 12 months (number TBR)
TUNIT27 = 'cm**(-2) s**(-1)' / units of field
TLMIN27 = 0.0 / minimum value
TLMAX27 = 1.0 / maximum value
TTYPE28 = 'Flux_Unc_History' / flux uncertainty (1-sigma, >100 MeV) history
TFORM23 = '12E' / floating point array, 12 months (number TBR)
TUNIT23 = 'cm**(-2) s**(-1)' / units of field
TLMIN23 = 0.0 / minimum value
TLMAX23 = 1.0 / maximum value
TTYPE29 = 'Hist_Start' / start of time intervals of flux history
TFORM29 = '12E' / floating point array, 12 months (number TBR)
TUNIT29 = 'd' / units of field
TLMIN29 = 0.0 / minimum value
TLMAX29 = 1.0D5 / maximum value
TTYPE30 = 'ID_Counterpart' / source counterpart (if any)
TFORM30 = '20A' / character string
TUNIT30 = 'none' / dimensionless
TTYPE31 = 'Conf_Counterpart' / confidence of association of counterpart with source
TFORM31 = 'I' / index, 1 = Figure of Merit, 2 = Correlated variability
TUNIT31 = 'none' / dimensionless
TLMIN31 = 0 / minimum value
TLMAX31 = 2 / maximum value
TTYPE32 = 'Flags' / flags (TBD) for catalog entry
TFORM32 = 'I' / integer
TUNIT32 = 'none' / dimensionless
END
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Comments on the draft of 26 October 2005
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(Luigi Foschini)
Keywords to add:
EXTREL: release number of the template for the FITS header, to take into account for future developments and changes in the header.
CREATOR: the name and version of the executable that generated the FITS file.
CONFIGUR: name and version of the software system under which the executable run (e.g. SAE v X.x).
DATE: date of the creation of the FITS file.
TIMEREF: time reference frame (LOCAL, SOLAR SYSTEM, etc...).
TIMEUNIT: I suggest to change to days (JD), so that to use MJDREF as TZERO and it is possible to avoid huge numbers; TSTART and TSTOP should be updated accordingly.
VERSION: version of the catalog.
RADECSYS: FK5 default; stellar reference frame.
EQUINOX: 2000.0 default; coordinate system equinox.
I would add also a new column "NOTES" (character string) where to place some comments, like, for example, other names of the sources (e.g. the corresponding name in the 3rd EGRET catalog, etc...).
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(Seth Digel, 30 December 2005)
I have updated the draft header above to take into account Luigi's comments. I also reformatted it to make it more like an actual template FITS header.
The updated draft includes DATE, TIMEREF, RADECSYS, and EQUINOX.
I omitted EXTREL because I believe the same information would be conveyed by HDUVERS.
CREATOR and VERSION are assumed to be in the main header for the file, which is not shown. To the extent possible we will have a common format for the primary headers of all our FITS data products; I intend to post a template for comment. CONFIGUR is assumed to be in the main header as well, with the name SOFTWARE
TIMEUNIT is changed to days, TIMESYS to 'MJD' and MJDREF is omitted. These changes, I think, permit the dates in the flux histories to be represented as MJD values. I think that we want these times in MJD rather than seconds of MET (as I had originally proposed) or as days with respect to January 1, 2001 (as Luigi proposed). Also I think that the description is correctly expressed in column 26 so that the duration of the interval used for the peak flux evaluation is in days. A detailed description of representing time in Chandra FITS files is available here (see section 2). I need to study it some more.
NOTES is omitted; the proposed use is good - especially for providing other names for identified sources - but how to make a NOTES column conveniently searchable or even figuring out how large a field to reserve is not clear. We'll have to revisit this.
Also, regarding flux histories, I am assuming that in columns 27 & 28, for intervals during which a source was not detected we'll have its flux entry as 0 and its flux uncertainty should be interpreted as a (2 sigma?) upper limit
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Comments on the draft of 26 October 2005
(Luigi Foschini)
Keywords to add:
EXTREL: release number of the template for the FITS header, to take into account for future developments and changes in the header.
CREATOR: the name and version of the executable that generated the FITS file.
CONFIGUR: name and version of the software system under which the executable run (e.g. SAE v X.x).
DATE: date of the creation of the FITS file.
TIMEREF: time reference frame (LOCAL, SOLAR SYSTEM, etc...).
TIMEUNIT: I suggest to change to days (JD), so that to use MJDREF as TZERO and it is possible to avoid huge numbers; TSTART and TSTOP should be updated accordingly.
VERSION: version of the catalog.
RADECSYS: FK5 default; stellar reference frame.
EQUINOX: 2000.0 default; coordinate system equinox.
I would add also a new column "NOTES" (character string) where to place some comments, like, for example, other names of the sources (e.g. the corresponding name in the 3rd EGRET catalog, etc...).
...